Small Engines (Lawn Mowers, etc.): lawnmower runs, doesnt cut, spark plug wire, rattling sound

Question
I have an old Toro w/ a bag (walker).  The engine runs fine, but when I engage the blades, I don't get the "vroom", the bag doesn't inflate, and the blades cut poorly or not at all.  Sometimes it will cut poorly for a few minutes and then suddenly begin working properly, but the last time I mowed, it never caught on.  It also started making a rattling sound when the blades were not engaged, as if something were out of adjustment. This has happened before, and I'm getting tired of taking it in. The higher the grass is, the worse the problem is. Is this a repair I could handle (a little experience)?

Answer
Hi Connie,

After disconnecting the spark plug wire, check the blade for any looseness and "right side up".  How do you engage or disengage the blades?  Do you know what happened the last time it was repaired?   

Let me know what you find.
Michael